1. Field of Invention
The present invention relates to use of bicistronic DNA constructs for identifying compounds that inhibits IRES-dependent translation activity of an infectious enterovirus (EV) or encephalomyocarditis virus (EMCV) without affecting CAP-dependent translation activity of a host subject. The compounds thus identified are useful in preparation of a medicament for treating an EV or EMCV infection.
2. Description of Related Art
Picornaviruses such as polioviruses, enterovirus, and encephalomyocarditis virus, are single stranded, plus-sense RNA viruses, which multiply in the cytoplasm of infected host cells by a unique mechanism involving internal entry of ribosomes near the initiator AUG (Pelletier et al., (1988) Nature 334, 320-325). Recent studies demonstrated that internal entry of ribosomes requires an element located between nucleotides 320-631 within the 5′UTR of poliovirus RNA (Pelletier et al., supra). This sequence element has been termed a ribosome landing pad (RLP) or, more generally, internal ribosome entry site (IRES). The picorna-related virus, such as hepatitis A and C, have also been shown to utilize internal ribosome entry site for translation initiation (Kohara et al., (1992) J Virol 66, 1476-1483 and Glass et al., (1993) Virology 193, 842-852) Furthermore, reports indicated that IRES sequence of Theiler's murine encephalomyelitis virus (TEMV) plays an important role on the virulence of the infectious virus (Sarnow (2003) Journal of Virology, 77, 2801-2806). For example, GDVII strains of TEMV with mutation on their IRES sequences are less virulent that those possess natural IRES sequences (Pilipenko, (2001) EMBO J. 20, 6899-6908). Taking together, the results above suggested that inhibition of IRES-dependent translation might be useful in treating these viral infections.
Inventors of this application unexpectedly found that bicistronic DNA constructs of infectious virus such as EV and EMCV may be used as a screening tool to identify compounds that inhibit IRES-dependent translation activities of these infectious viruses. The compounds thus identified, e.g., amantadine, will be useful in preparation of a medicament for treating EV or EMCV infection.